That may be a rebutable presumption but it is also at the core of the debate at hand. The longer term consequences of illegal immigration lends compelling evidence for the need to act with haste.
Children born in the United States to illegal aliens, the children of those anchor babies and in turn their third generation, US citizens are still the consequence of illegal immigration and they are part and parcel of the problems created by unregulated immigration.
These second, third and now fourth generation progeny are, in fact, the chief contributor to the overcrowding in California's public schools, public medical facilities and prison systems. They are, numerically , the plurality in California's gang population which represents the single largest item in California's expenditure for law enforcement, adjudication and incarceration.
The estimate offered, whether accurate or embellished, focuses on a pivotal aspect of the debate over the regulation of immigration. The revision, by Roosevelt era judges, of the original intent of the "under the control of" clause in the 14th Amendment, needs sorely to be challenged and reviewed at the SCOTUS.